How to get the name of the running function/method when executing a class method?

Hello everybody,

I have a class with several methods and I want to write my own log-file which tells me if the executed methods threw an error or not. I have a function to save a success-parameter, with a timestamp and the name of the executed method, but how do I get the name of the running method to pass it to the log-function?

I know that I could just type in the name of the method in the function call by hand for every method, but I'm hoping for a better solution.

classdef classname
  methods
      function test( obj )
          write2log( 'test' );    % instead of 'test' there should be a function
                                  % which returns the name of the current function/method
      end
  end
end

mfilename does not work because it will only give me the name of the m-file, which is the name of the whole class.

Thanks for your help,

Tom

(MATLAB version: Matlab R2016b)

Answer 1

[Ameer Hamza]

You can use dbstack. It returns function call stack as a struct array. Since you want the name of the lastest function in the call stack, you will need to access the first element of the struct array as shown below

funCallStack = dbstack;
methodName = funCallStack(1).name;

functionName name will have a format like this: '(class_name).(method_name)', you can use strsplit() to seperate the method name

methodNameSeperate = strsplit(methodName, '.');
methodName = methodNameSeperate{end};

[Tom Wenk]

Where do I have to define funCallStack?

When does this functionality add a field to the struct? When entering the method/function or when it is done? I tried to use it, but the struct is not filled, when I execute the method..

As far as I understood the dbstack functionality, it is used with setting breakpoints in the code, is that right?

[Ameer Hamza]

No, it returns the function call stack (i.e. the complete list nested functions as they are called). You can experiment with it by saving this simple function on your MATLAB path and see the output after running.

function test_()
 disp(dbstack);
end

What did you get?

[Stephen23]

"As far as I understood the dbstack functionality, it is used with setting breakpoints in the code, is that right?"

While it is commonly used when debugging, in fact dbstack can be called at any time. It returns the stack of function calls that resulted in the code getting to the position where it is currently executing, i.e. where dbstack is being called from. Note that introspective programming like this does slow down code.

[Guillaume]

Personally, I'd just hardcode the function name in the write2log code, rather than use dbstack (which as Stephen pointed out will slow down the execution). But if you were to use dbstack you'd implement it like this:

classdef classname
  methods
      function test( obj )
          write2log();
          %....
      end
  end
end

function write2log
    stack = dbstack(1, '-completenames');  %completenames optional. Use 1 to bypass write2log in the call stack
    fprintf('%s: %s\n', datetime, stack(1).name);
end

[Tom Wenk]

Thanks to all of you guys, I got it working for me! :)

Is there a big performance drop when I use this?